Studying the scalar bound states of the $K\bar K$ system in the Bethe-Salpeter formalism

Understand

We study the possible bound states of the $K\bar K$ system in the Bethe-Salpeter formalism in the ladder and instantaneous approximations.

• We find that the bound states exist.
• However, these bound states have very small decay widths.
• Therefore, besides the possible $K\bar K$ component, there may be some other structures in the observed $f_0(980)$ and $a_0(980)$ .